Abudefduf sexfasciatus

The scissortail sergeant, also called the striptailed damselfish (Abudefduf sexfasciatus), is a sizable member of the Pomacentridae family. Its common name comes from the black stripes on its tail and sides, which resemble a military sergeant’s insignia and look similar to those of the sergeant major damselfish. This fish is white with five vertical black bands and two horizontal bands on its tail lobes. It can reach a maximum length of 22 centimeters (8.7 inches) and typically grows to about 16 centimeters (6.3 inches). Scissortail sergeants inhabit coral reefs in tropical waters, often forming groups around a single coral head, at depths from 1 to 20 meters (3.3 to 65.6 feet). They are found across the Indo-Pacific, including the Red Sea, eastern Africa, Madagascar, the Seychelles, the Persian Gulf, India, Sri Lanka, the Bay of Bengal, the Andaman Sea, Indonesia, Australia’s Great Barrier Reef, the Gulf of Thailand, the Philippines, Taiwan, Japan, various Pacific islands as far as Hawaii, and a single 2017 record near Athens, Greece, likely from an aquarium release. Adults live on coral reefs, while younger individuals stay in the open sea.

This species feeds on algae, zooplankton, and sometimes its own eggs, and it also consumes invertebrate larvae, smaller fish, and crustaceans. It is preyed upon by some fish in the Labridae and Serranidae families. In the wild, scissortail sergeants aggregate in large groups above coral. They are popular in the aquarium trade but are very aggressive and difficult to keep with other similarly sized fish.

For reproduction, females lay eggs in patches on a firm substrate, and males guard them vigorously until they hatch. Males are polygamous, collecting eggs from up to 12 females, who spawn and then abandon their eggs. Males handle all parental care, which is common in fish because territorial males can guard multiple clutches while attracting new mates. Males undergo brood cycling, alternating between a mating phase—where they turn gold and display to attract females—lasting two to three days, and a four- to five-day parental phase, during which they guard the eggs. Filial cannibalism, eating their own offspring, occurs in the parental phase. To select good fathers, females pool their eggs with others in a single male’s territory, creating larger broods that reduce predation risk and discourage male cannibalism.